86 lines
3.7 KiB
C#
86 lines
3.7 KiB
C#
// Copyright 2025 Code Philosophy
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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using Obfuz.Utils;
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using System.Collections.Generic;
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namespace Obfuz.EncryptionVM.Instructions
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{
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public class XorMultipleRotateInstruction : EncryptionInstructionBase
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{
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// x = x ^ p3 ^ salt;
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// x = x * p1 + secretKey[index1];
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// x = Rotate(x, p2)
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private readonly int _multipleValue;
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private readonly int _revertMultipleValue;
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private readonly int _index1;
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private readonly int _rotateBitNum;
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private readonly int _xorValue;
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public XorMultipleRotateInstruction(int xorValue, int multipleValue, int index1, int rotateBitNum)
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{
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_multipleValue = multipleValue;
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_revertMultipleValue = MathUtil.ModInverse32(multipleValue);
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_index1 = index1;
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_rotateBitNum = rotateBitNum;
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_xorValue = xorValue;
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}
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public override int Encrypt(int value, int[] secretKey, int salt)
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{
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value ^= _xorValue ^ salt;
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value = value * _multipleValue + secretKey[_index1];
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uint part1 = (uint)value << _rotateBitNum;
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uint part2 = (uint)value >> (32 - _rotateBitNum);
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value = (int)(part1 | part2);
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return value;
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}
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public override int Decrypt(int value, int[] secretKey, int salt)
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{
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uint value2 = (uint)value >> _rotateBitNum;
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uint part1 = (uint)value << (32 - _rotateBitNum);
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value = (int)(value2 | part1);
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value = (value - secretKey[_index1]) * _revertMultipleValue;
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value ^= _xorValue ^ salt;
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return value;
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}
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public override void GenerateEncryptCode(List<string> lines, string indent)
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{
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lines.Add(indent + $"value ^= {_xorValue} ^ salt;");
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lines.Add(indent + $"value = value * {_multipleValue} + _secretKey[{_index1}];");
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lines.Add(indent + $"uint part1 = (uint)value << {_rotateBitNum};");
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lines.Add(indent + $"uint part2 = (uint)value >> (32 - {_rotateBitNum});");
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lines.Add(indent + $"value = (int)(part1 | part2);");
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}
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public override void GenerateDecryptCode(List<string> lines, string indent)
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{
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lines.Add(indent + $"uint value2 = (uint)value >> {_rotateBitNum};");
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lines.Add(indent + $"uint part1 = (uint)value << (32 - {_rotateBitNum});");
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lines.Add(indent + $"value = (int)(value2 | part1);");
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lines.Add(indent + $"value = (value - _secretKey[{_index1}]) * {_revertMultipleValue};");
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lines.Add(indent + $"value ^= {_xorValue} ^ salt;");
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}
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}
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}
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